Dry disconnect couplings are used in various applications to connect one fluid conduit to another to form a continuous flow path. For example, dry disconnect couplings are used to form a continuous flow path between a storage tank and a tanker truck to transfer caustic chemicals or petroleum products at a storage tank farm. Typically, the dry disconnect coupling includes an adapter and a coupler. One end of the adapter is attached to the fill pipe of the tanker truck, and one end of the coupler is attached to a transfer hose from the storage tank. The free end of the adapter is then connected to the free end of the coupler to complete the coupling. When coupled together, the adapter and the coupler define a flow passageway therethrough that is sealed by a pair of internal poppet valves having opposed faces. The continuous flow path is established by displacing the poppet valve of the coupler in the direction of the poppet valve of the adapter to open the coupling.
When the fluid, for example a caustic chemical solution, is transferred from the storage tank to the tanker truck, residual fluid may collect around the periphery and on the face of the poppet valve of the adapter and the poppet valve of the coupler. This residual fluid may inadvertently be spilled onto the ground when the adapter and the coupler are disconnected, and accordingly, is referred to hereinafter as "the loss at disconnect". Although the loss at disconnect that may be spilled after each fluid transfer operation is generally less than an ounce, repeated fluid transfer operations can result in significant contamination of the ground in the vicinity of the coupling. In fluid transfer operations involving caustic chemicals, any amount of ground contamination is particularly unacceptable because the chemicals may be toxic to the environment and to individuals handling the coupling. It is therefore desirable to minimize the loss at disconnect to prevent caustic chemicals and other environmentally hazardous fluids from contaminating the ground in the vicinity of the coupling.
Contamination of the ground in the vicinity of the coupling may also occur when a "side load" is applied to the coupling. The term "side load" as used herein refers to a force which is applied in any direction other than along the longitudinal axis of the coupling, and which therefore produces a bending moment about the longitudinal axis. For example, the influence of gravity on the center of mass of the coupling produces a bending force about the longitudinal axis that may be significant enough to cause the coupling to leak during a fluid transfer operation. Similarly, a handling force applied to the coupling, or at a point on the transfer hose adjacent to the coupling, in a direction other than along the longitudinal axis may cause the coupling to leak during a fluid transfer operation. A side load may also separate the face of the poppet valve of the adapter from the face of the poppet valve of the coupler, thus permitting additional fluid residue to accumulate on the faces of the poppet valves which contributes to the loss at disconnect.
Additional contamination of the ground in the vicinity of the coupling may also occur as the mechanical components of the means for connecting the adapter to the coupler become worn. Initially, the connection between the adapter and coupler is rigid and fluid-tight. However, after the adapter and the coupler have been connected and disconnected numerous times, the connection may become "loose" and cause the coupling to leak during a fluid transfer operation. In some coupling designs, the connection becomes loose after the adapter and the coupler have been connected and disconnected only a few times. Accordingly, external means for collecting the fluid as it leaks from the coupling must be utilized to prevent the fluid from contaminating the ground in the vicinity of the coupling.
A conventional dry disconnect coupling is disclosed in U.S. Pat. No. 5,273,071 issued Dec. 23, 1993, to Oberrecht. The Oberrecht coupling includes an adapter and a coupler that, when coupled together, define a flow passageway therethrough. The adapter and the coupler each include an internal poppet valve. When closed, the poppet valves seal the coupling. When opened, the poppet valves permit fluid to flow through the flow passageway defined by the adapter and the coupler to establish a continuous flow path. The Oberrecht coupling is further provided with an O-ring mounted in a groove formed in the face of the poppet valve of the coupler. When the poppet valve of the coupler is displaced in the direction of the adapter, the O-ring forms a seal with the face of the poppet valve of the adapter to prevent the faces of the poppet valves from being wetted during a fluid transfer operation. Thus, the O-ring minimizes the amount of fluid residue that accumulates on the poppet valves and contributes to the loss at disconnect.
Fluid residue may still, however, accumulate around the periphery of the faces of the poppet valves of the Oberrecht coupling. This fluid residue is not returned to the flow path or to an external reservoir, but instead migrates around the periphery of the poppet valves under the influence of gravity and collects inside the coupling opposite the ground. When the adapter and the coupler are subsequently disconnected, the fluid residue spills onto and contaminates the ground in the vicinity of the coupling. Further, the O-ring of the Oberrecht coupling may become worn. If not replaced, the O-ring may leak and permit additional fluid residue to collect on the faces of the poppet valves of the coupler and the adapter. This additional fluid residue may likewise contribute to the loss at disconnect.
Another example of a dry disconnect coupling is disclosed in U.S. Pat. No. 5,628,344 issued May 13, 1997, to Roberts and assigned to the assignee of the present invention. The coupling includes an adapter and a coupler that, when coupled together, define a flow passageway therethrough. The Roberts coupling further includes means for returning fluid residue that accumulates around the periphery and on the faces of the poppet valves directly to the flow passageway or to an internal holding chamber. The returning means includes a reservoir for collecting the fluid residue that drains (under the influence of gravity) from the poppet valves of the adapter and the coupler after a fluid transfer operation. In one embodiment, the returning means further includes a venturi vacuum for suctioning the fluid residue out of the reservoir and back into the flow passageway during a subsequent fluid transfer operation. In another embodiment, the returning means further includes aspirating and pumping means for first suctioning the fluid residue out of the reservoir into a holding chamber, and then pumping the fluid residue out of the holding chamber and back into the flow passageway during a subsequent fluid transfer operation.
The dry disconnect coupling disclosed in U.S. Pat. No. 5,628,344 is essentially fluid-tight under normal operating conditions, and therefore minimizes the loss at disconnect. However, when the poppet valves of the coupler and the adapter are opened and closed before and after a fluid transfer operation, respectively, there remains an opportunity for fluid residue to accumulate around the periphery and on the faces of the poppet valves. There is likewise an opportunity for fluid residue to accumulate on the faces of the poppet valves when a side load is applied to the coupling or to the transfer hose adjacent the coupling. This fluid residue may then spill onto the ground when the adapter and the coupler are disconnected if the fluid residue has not completely drained from the faces of the poppet valves into the reservoir.
As disclosed in U.S. Pat. No. 5,407,175 issued Apr. 18, 1995, to Roberts, the adapter of the coupling preferably includes a rotatable annular flange for attaching the adapter to the coupler. The flange is rotatable to facilitate repositioning of the flange relative to the circumferentially spaced latching lugs of the coupler, and to thereby distribute wear evenly on the flange. Thus, a rigid, fluid-tight connection is maintained while the service life of the adapter is extended. However, the flange must be inspected at regular intervals and rotated, if necessary, to prevent the connection from becoming loose over time. Further, if not replaced, the flange may eventually become sufficiently worn (despite being rotated at regular intervals) to cause the coupling to leak during a fluid transfer operation.
Accordingly, it is apparent that there is a need for a fluid coupling for connecting one fluid conduit to another to form a continuous, essentially fluid-tight flow path. In particular, there is a need for a fluid coupling that does not leak when a force is applied in any direction other than along the longitudinal axis of the coupling, or when the mechanical components of the coupling become worn after connecting and disconnecting the adapter and the coupler more than a few times. Likewise, there is a particular need for a fluid coupling that prevents fluid residue from accumulating on the faces of the poppet valves of the adapter and the coupler during a fluid transfer operation.
Therefore, it is a principal object of the present invention to provide a fluid coupling for connecting one fluid conduit to another to form a continuous, essentially fluid-tight flow path.
It is another, more particular, object of the invention to provide a dry disconnect coupling which includes improved connecting means for providing a rigid, essentially fluid-tight connection between the adapter and the coupler to prevent a side load applied to the coupling from causing fluid to leak during a fluid transfer operation.
It is another, more particular, object of the invention to provide a dry disconnect coupling which includes improved connecting means for providing a rigid, essentially fluid-tight connection between the adapter and the coupler to prevent wear of the mechanical components of the coupling from causing fluid to leak during a fluid transfer operation.
It is another, more particular, object of the invention to provide a dry disconnect coupling which includes improved sealing means for preventing fluid residue from accumulating on the faces of the poppet valves of the adapter and the coupler during a fluid transfer operation.
It is another, more particular, object of the invention to provide a dry disconnect coupling which includes improved releasing means for releasing the connecting means of the coupling to disconnect the adapter and the coupler.
It is yet another, more particular, object of the invention to provide a coupler for a dry disconnect coupling which includes improved connecting means for providing a fluid-tight connection between the adapter and the coupler so as to essentially eliminate the possibility that fluid residue may leak during a fluid transfer operation.
It is yet another, more particular, object of the invention to provide a coupler for a dry disconnect coupling which includes improved sealing means for preventing fluid residue from accumulating on the faces of the poppet valves so as to essentially eliminate the possibility that fluid residue may spill when the adapter and the coupler are disconnected and contaminate the ground in the vicinity of the coupling.